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Answer 1

A:

Maybe just run it, use it, and see what goes wrong. The greater challenge will be how to fill the data dynamically, from some database, since your stock of supplies will change regularly.

As for posting the data to the server, be sure that on the server you re-check everything, i.e. don't rely on anything your javascript does - it can easily be tweaked by a malicious user.

mvds 2010-07-18 09:46:33

I just have a question , if a code does the same thing just like another code did , and the code is shorter , is it the shorter one is the more efficient code??

2010-07-18 10:09:17

not necessarily. You can take a car, drive 100 miles and arrive earlier at your destination compared to walking 50 miles in a straight line - what would be more efficient? in other words: it totally depends on your goals.

mvds 2010-07-18 10:17:22

Answer 2

+1 A:

The code would be more flexible, if you use a pointer to the clicked element itself, instead of giving the index of the element to the update-functions. You can achieve this by changing the onclick-attribute from onclick="Addlist_onclick(0)" (or any other index) to onclick="Addlist_onclick(this)" and changing the Addlist_onclick code a bit:

function Addlist_onclick(node)
{
    var comp = node.form;
    var count;
    var position;

    switch(node.name)
    {
        case "process": position = 0;
                        break;
        case "Hard":        position = 1;
                        break;
        default:            position = 2;
                        break;
    } 

    comp.list.options[position].text = node.value;

    count = comp.list.options[position].text.lastIndexOf("RM");

    comp.list.options[position].value = comp.list.options[position].text.substr(count + 2);

    comp.totalPrice.value = null;
}

You can improve AddCmp_onclick in a similar way, but I leave this as an exercise to you ;)

How it works in detail: In Javascript you can use the this-pointer if you need a reference to the current context (the object the method is part of). If you you simply declare a function inside a script-tag (like you did with Addlist_onclick), the declared function becomes a method of the window object. Therefore this would point to window.

However, if you add an event handler to a html-node through an attribute like onclick, the javascript-interpreter first calls a generic event-handling method of the clicked html-node, which then calls the function you've defined in the attribute. Therefore the this points to the clicked html-node when Addlist_onclick(this) is executed. Inside Addlist_onclick the this-pointer points to window again, since your function is not a method of the clicked-node but of the main-window (as explained above).

Le Torbi 2010-10-02 14:08:22

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